When looking for round end caps, foot glides and inserts for your outdoor furniture, first determine the size of the tube. Measure the outside diameter (O.D.) of the tube, though a few parts are measured by the tube’s inside diameter (I.D.) Click on a part, and the description will explain which diameter the part fits. Measuring the part itself will yield a size that won't fit. Most of our round parts are shown below in order of size. Along with multi-gauge parts to fit a variety of sizes, you'll find parts that have domed and flat surfaces.